Oenothera clelandii W.Dietr., P.H.Raven & W.L.Wagner
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Erect or ascending biennial 4–10 dm; lvs linear to narrowly lanceolate or linear-oblong, 3–8 cm, entire or remotely and obscurely denticulate, short- hairy on both sides; fls autogamous, numerous, crowded in a terminal, leafy-bracteate spike 1–3 dm; hypanthium 1.5–3 cm, sparsely strigose; sep linear, 0.5–1.5 cm, reflexed separately or ± connivent; pet yellow, 0.5–1.5(–2) cm, broadly elliptic or ovate, usually acute; fr linear, 10–18 mm, usually curved; seeds dark brown, obovoid or fusiform, obscurely pitted; 2n=14, a complex heterozygote. Fields and prairies in sandy soil; Mich. to Minn., Io., Ill., and Ind., and irregularly to Ark., Ky., N.J., and N.Y. June–Sept. (O. rhombipetala, in part)